Lead Poisoning

Photo by: Laurence Gough

Lead is an indestructible
heavy metal
that can accumulate and linger in the body. Although the problem of lead
exposure has been reduced in the United
States, minorities and disadvantaged individuals remain chronically
exposed. In developing countries, occupational and environmental exposures
still exist and are a serious public health problem.

Definition of Lead Poisoning

Lead poisoning, or plumbism, is defined as a toxic condition caused by the
ingestion or inhalation of the metallic element lead, which is found in
many places, including the air, soil, water, houses, ceramic cookware, and
solder used in metal cans and pipes. Lead poisoning occurs when blood lead
levels are equal to or greater than 10 μg/dl (micrograms per
deciliter).

Symptoms of Lead Poisoning

Lead exposure results from either inhaling or ingesting lead. Low levels
of exposure (up to 10 μg/dl) are associated with
anemia
, headaches, general weakness,
fatigue
, learning disabilities, impaired
development
of the
nervous system
, and delayed growth, while greater levels of exposure (70 μg/dl)
include symptoms such as decreased appetite, vomiting, abdominal pain,
constipation
, and drowsiness. If blood lead levels exceed 70 μg/dl, coma,
seizures, bizarre behavior, impaired muscular coordination, and even death
can occur.

Populations at Risk

Lead poisoning is one of the greatest environmental threats to children.
Lead
absorption
is five to eight times greater in children than in adults. Approximately
11 percent of ingested lead will reach the adult digestive tract, as
compared to 30 to 70 percent in children. In addition, children absorb up
to 50 percent of inhaled lead. Children that are at greatest risk are
those living near highways and interstates, in urban and inner-city areas,
or in low-income housing. While the United States government banned leaded
gasoline in 1986, residual lead is still present in the soil around
highways and interstates. Children that live in homes or play in
playgrounds near those areas can ingest lead through dust on their hands.
In developing countries where leaded gasoline is still used, children
living near highways are exposed to lead through automobile and truck
exhaust.

Children living in inner-city and urban areas are exposed to lead through
leaded paint used in older homes (prior to 1978), as well as through the
presence of pipes soldered with lead solder. Lead can leach into the water
in the pipes, contributing to the blood lead levels of children (and
adults) ingesting the water. The major sources of lead exposure today are
household dust from paint and exterior soil. In addition, children of low
socioeconomic status
are at a nutritional disadavantage, for they often do not consume enough
food to keep their stomachs full enough to slow absorption, and because
they usually do not have enough
iron
and
calcium
in their diets.

In developing countries, both adults and children face a risk of lead
poisoning due to exposure sources such as leaded gasoline, lead-based
cosmetics, lead solder in food containers, ceramic cookware, folk
remedies, and lead-based paint. Since adverse effects of lead poisoning
are magnified in
malnourished
populations, it is critical that developing countries recognize the
threat of unintentional lead exposure.

Lead is commonly found in and around the home, especially in older
homes. Children are especially susceptible to lead poisoning, since
they absorb lead more readily than adults. Even minor exposure to lead
can severely affect a child's development.

[Electronic Illustrators Group. Reproduced by permission.]

Sources of Lead

During the 1970s, Americans discontinued the use of leaded gasoline, and
other sources of environmental lead exposure have gradually been reduced.
While exposure to lead has diminished, residual amounts still remain in
contaminated soil, dust, lakes, and streams.

A major source of environmental exposure for children is lead-based paint.
While this type of paint is no longer manufactured in the United States,
buildings constructed prior to 1978 may contain residual lead. Lead
exposure occurs when lead-contaminated dust is inhaled or ingested. In
addition, young children may eat contaminated paint chips or ingest
contaminated paint dust while sucking their hands or fingers.

Other sources of lead exposure include ceramic cookware and lead solder.
Lead contained in the glaze on ceramic cookware can leach out and enter
food during the cooking process. In lead-soldered pipes, lead enters the
water as it passes through or collects in the pipe. People living in older
homes with lead-soldered pipes should drink bottled water or make certain
that the water is allowed to run several minutes before it is ingested.
Water that has sat in the pipes longer than six hours should not be
consumed.

While lead solder is no longer used to seal cans in the United States,
imported food remains a source of exposure. Once again, lead from the
solder leaches into the food. Acidic foods and drinks, such as pickles or
fruit juice, enhance the leaching process. Other exposure sources include
a food coloring (
lozeena
) from Iraq that is sometimes used to color rice and meat, and to which
lead is sometimes added; prune juice concentrate from France and raisins
from Turkey (lead-containing preservatives and pesticides are used on
foods such as prunes and raisins), and duck eggs from Taiwan (lead is used
in the traditional method of preserving duck eggs). In addition, a
number of folk remedies from around the world, as well as imported leaded
crystal, can be sources of lead exposure. Folk remedies of concern
include:
koo sar
pills, used as a remedy for menstrual cramps in Asia;
azarcon,
an orange powder used for intestinal illness in Mexico;
ghasard,
an Indian folk remedy for babies;
kandu,
a red powder used to treat stomachache;
farouk,
a Middle Eastern teething remedy; and
hai gen fen,
a clamshell powder added to tea.

Nutritional Interventions

Nutritional deficiencies
allow lead to accumulate in body tissues and organs. The absorption of
lead is greatest when the stomach is empty; therefore, consuming regular
meals is important. Unfortunately, the ability to afford three meals a day
is sometimes a problem for populations at risk for lead poisoning.

In the body, calcium binds to lead and inhibits its absorption; therefore,
dietary calcium interferes with the absorption of lead through the
intestinal
mucosa
. Among high-risk populations, calcium supplements or the addition of milk
and yogurt to meals and snacks is recommended.

Research has also demonstrated a link between iron deficiency and lead
poisoning. Recognition of this link is important, since iron deficiency is
the most common childhood nutritional problem worldwide. Iron
supplementation, or consuming foods rich in iron, such as
fortified
cereals, prunes, beef, and calves liver, can interfere with lead
accumulating in the body.

Educational Interventions

In many developed nations, information programs are available to advise
homeowners of lead hazards in older homes. Programs offering proper
methods of exposure reduction are important, since homeowners attempting
to rid their homes of lead paint and pipes with lead solder can
inadvertently increase their exposure through sanding and other
activities. International groups, such as the World Health Organization,
are working to increase international awareness of lead exposure issues
and abatement programs. In 1998, the U.S. National Center for
Environmental Health identified childhood lead poisoning as one of its
five global priorities.

The most effective intervention for lead poisoning is removing all sources
of lead from the
environment
. Since this is not possible for many high-risk populations, health care
providers can provide parents and child-care workers with information on
how to care for children's nails and on proper hand-washing
techniques, as well as information on the dangers of consuming paint chips
and/or paint dust.

Consumer-awareness campaigns relating to the potential hazards of imported
cookware and dishes can also help adults and children avoid unintentional
ingestion of lead. Individuals need to be aware of the potential presence
of lead in products and food items from other countries, particularly
those that lack environmental controls relating to lead, such as Mexico,
Turkey, Pakistan, India, Indonesia, Nepal, Thailand, and many countries in
the Middle East and Asia.

Prevalence of Lead Poisoning

As a result of public health initiatives, lead levels in
children's blood have dropped steadily since the 1970s, but
approximately 434,000 U.S. children between one and five years of age
still have elevated lead levels. Lead poisoning remains a particular
threat among certain racial and ethnic groups that are
disproportionately affected. For example, 6 percent of white children
living in older housing have elevated lead levels, while the numbers for
African-American and Mexican-American children in similar housing are 22
percent and 13 percent, respectively. In developing countries, which
commonly use unleaded gasoline, lead poisoning is the most significant
environmental disease among children. According to the World Health
Organization, fifteen to eighteen million children in the developing
world have suffered permanent brain damage as a result of lead
poisoning.

—Paula Kepos

Medical Treatment

Typically, persons diagnosed with blood lead levels greater than 45
μg/dl will receive chelation therapy, which uses chemical agents
that bind to lead
in the body and cause it to be excreted in the urine or feces. High blood
lead levels are considered a medical emergency requiring immediate
attention, since the chances of serious complications rise as lead
accumulates in the blood.

User Contributions:

i am a food technology student and now im currently work for an on job trainee in a food company here in the philippines in our experiment for some analysis in sugar in particular food product we used lead acetate both the powder and the liquid.. what should i do in order for me to minimized this kind of chemicals???and what teatment in order to lessen the lead content that i inhaled during the analysis or some food suppleent???

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